This book sketches a picture of the process of regional integration in Europe without sacrificing rigour, while retaining as much of the specific features of the countries involved as possible. Its aim is to empirically investigate the introduction of a single currency in the EU and the potential enlargement towards Central and Eastern Europe, individually and in their interaction. The emphasis is on integrating the existing theoretical developments on regional economic and monetary integration and using them as the framework for a comprehensive exploratory analysis. The purpose of the analysis is to offer some preliminary answers to questions such 1. Are the objectives of the EU compatible with the policy instruments available (at European and at national level)? 2. Are the European objectives compatible with the national objectives of the EU15 member states? 3. Are the objectives of ‘deeper’ integration (single currency) and ‘wider’ integration (enlargement) compatible with each other, given the instruments available? 4. Which are the member states most likely to benefit from the introduction of the single currency and what distinguished between potential losers and potential gainers? 5. Do the existing and the potential EU members belong to different ‘natural’ groups, determined by their intrinsic characteristics? What distinguishes between such groups?